I have a 2002 high efficiency furnace,,not sure what model,,says 91% efficiency on the side. When it's running it randomly makes a noise as if it shuts off and starts really quickly but keeps running. The Furnace guy was here and checked everything and said everything looks good and he thinks" its a relay clicking on and off really quick" on the PCB and says just to keeps using it and see what happens,,, as the boards for these furnaces are around 500$!! any of you guys run into this?